Typical automotive speaker systems include door mounted speakers that are often mounted in the lower front portion of the door for satisfactory acoustic performance. A common method of mounting the speakers is to form mounting openings in the frame or basket that supports the diaphragm and fasten the assembly to the inner door panel using screws or other suitable fasteners, FIG. 4A. The resulting speaker and audio system performance is influenced by, and dependent upon the stiffness of the vehicle interface. In most cases the acoustic performance of the speaker is improved as the stiffness of the mounting interface is increased however, often the vehicle interface lacks sufficient stiffness which degrades speaker performance. Specifically, low-frequency (bass) output and maximum sound pressure level are decreased, having an overall negative impact on vehicle level audio system performance. In addition, the speaker can induce mechanically coupled energy “E” to the door system through structurally less rigid, or more flexible areas of the door panel resulting in speaker induced vibration of the door inner panel and other components which mount thereto (ex. window lift system, door trim, rain paper, locks systems, etc.).
Several design features have been used to improve the stiffness of the vehicle-speaker interface including forming rolled edges or flanges around the speaker mounting holes, adding formations around the speaker interface, and increasing the mounting panel thickness however the improvement is typically small. The structural improvement is typically limited to the physical forming capability of the area in which the speaker is mounted and areas closely adjacent thereto.